Step-by-step explanation:
Octet rule is defined as the rule in which an atom in order to attain stability needs to have eight electrons in its outermost shell.
For example, atomic number of sodium is 11 and its electronic distribution is 2, 8, 1.
So, in order to acquire stability it just needs eight electrons in its outermost shell. Since, there is only one electron in its outermost shell and it is very difficult or impossible for a sodium atom to gain 7 electrons.
Therefore, it readily loses one outermost electron and becomes stable in nature.
This system of acquiring stability actually shows the chemical behavior of an atom or we can say that it shows reactivity of an atom.
Therefore, we can conclude that depending on whether atoms satisfy the octet rule will predict chemical behavior of the atoms.